The energy costs for railways are significant. By driving efficiently, these costs can be significantly reduced.
There are five main principles of efficient driving:
1. Aim to arrive on time. If you arrive early you have already wasted energy; if you arrive late you will waste energy making up the lost time.
2. Calculate your required average speed. On long journeys, simply dividing the distance remaining by the time remaining will give you an approximate holding speed. Recalculate during the journey to make sure you are still on target.
3. Aim to drive at a constant speed. Speed fluctuations waste energy. The most efficient way to drive is to aim for a constant speed.
4. Avoid braking at high speeds. Braking at high speeds is inefficient. Instead, coast to reduce your speed before declines and speed limits.
5. Anticipate hills. If the train is going to slow down on a steep incline, increase your speed before the incline so that the average speed on the incline does not drop too far below the hold speed. For steep declines, coast before the decline so that the average speed does not rise too far above the hold speed. Avoid braking.
A train journey can be divided into segments between “targets”, that is, locations on the route where the time and speed are specified. There are many driving strategies that may be used to operate a train between one target and the next. One strategy is a “speed-holding” strategy, where a constant speed is maintained, except where prevented by speed limits and steep gradients. In practice, of course, speed limits and steep gradients can disrupt a significant part of a journey. If an efficient journey for a given holding speed V can be determined then V can be adjusted to find the efficient journey that satisfies the journey time constraint; if the time taken is too long then V is too low. In determining an appropriate holding speed it is possible to generate points on a cost-time curve for the journey.
Using this methodology a journey with holding speed V can be constructed as follows:                1. Ignoring speed limits and the initial and final speeds, construct a speed-holding journey with holding speed V. The speed of the train will vary with steep gradients.        2. Adjust the speed-holding journey to satisfy the speed limits.        3. Construct initial and final phases to satisfy the initial and final speed constraints.        
However, using this methodology may not result in the most energy-efficient journey.
It is therefore an object of the present invention to provide a method and system for operating trains which overcomes or ameliorates at least one of the disadvantages of the prior art, or at least provides a useful alternative.